Control unit for minimizing water and power consumption in automatic film processors

ABSTRACT

An automatic film processor is provided with a control system for inhibiting the drier heater and blower motor circuits unless film is being transported through the processor, to save electrical power, and to prevent wash water from flowing to waste except while film is being transported, in order to effect reduction of water consumption. The control system includes a pulse generator producing a train of pulses related to the rate of film transport through the processor; a film feed sensor for monitoring the presence or absence of a sheet of film at the input tray of the processor; a first counter, preferably taking the form of a slow integrator, which is activated by passage of the trailing edge of a sheet of film past the film feed sensor and which operates to count pulses from the transport pulse generator to produce an output signal operative to energize the drier heater and blower motor circuits and water solenoid for a period of time, determined by the transport speed and film length, sufficient to allow the trailing edge of the film to reach the catch tray at the output of the processor; and a second counter, preferably taking the form of a fast integrator, activated by passage of the trailing edge of the sheet of film past the film feed sensor for counting a series of pulses from the transport pulse generator and operative to indicate when a further sheet of film can be fed into the processor with constant trailing edge to leading edge space separation between the film sheets.

llnited States Patent [191 Manaclr et al.

[ CONTROL UNIT FOR MINIMIZING WATER AND POWER CONSUMPTION IN AUTOMATIC FILM PROCESSORS [75 l Inventors: Anthony W. Manack, Springfield;

Michael A. Sulak, Woodbridge, both of Va.

[73 l Assignee: Logetronics Inc., Springfield, Va. [22] Filed: Sept. 25, 1972 [21] Appl. No.: 291,927

2,296,048 9/1942 Planskoy 95/89 R 3,442,589 5/1969 lshikawa et al. 95/89 R X 3,487,763 l/l970 Pensgen 95/89 R Primary Examiner-Fred L. Braun Att0rney-William D. Hall et al.

[57] ABSTRACT An automatic film processor is provided with a control Light Deteclorlb Main Drive Shaft of Processor Transport Mechanism One Shot Pulse Genr.

system for inhibiting the drier heater and blower motor circuits unless film is being transported through the processor, to save electrical power, and to prevent wash water from flowing to waste except while film is being transported, in order to effect reduction of water consumption. The control system includes a pulse generator producing a train of pulses related to the rate of film transport through the processor; a film feed sensor for monitoring the presence or absence of a sheet of film at the input tray of the processor; a first counter, preferably taking the form of a slow integrator, which is activated by passage of the trailing edge of a sheet of film past the film feed sensor and which operates to count pulses from the transport pulse generator to produce an output signal operative to energize the drier heater and blower motor circuits and water solenoid for a period of time, determined by the transport speed and film length, sufficient to allow the trailing edge of the film to reach the catch tray at the output of the processor; and a second counter, preferably taking the form of a fast integrator, activated by passage of the trailing edge of the sheet of film past the film feed sensor for counting a series of pulses from the transport pulse generator and operative to indicate when a further sheet of film can be fed into the processor with constant trailing edge to leading edge space separation between the film sheets.

Monuol Override Switch? Detector Film Feedin Bb Lamp- 4 gontrolled Circuils- 7 eotersfilower Water Solenoidfih er Source CONTROL UNIT FOR MINIMIZING WATER AND TOWER CONSUMPTION IN AUTOMATIC FILM PROCESSORS BACKGROUND OF THE INVENTION Control units have been suggested heretofore, for use in conjunction with graphic arts film processors, to effect various energy-saving functions therein, namely the saving of electrical power by inhibiting the drier heater and blower motor circuits unless film is being transported through the processor, and to effect a reduction of water consumption by preventing wash water from flowing to waste except while film is being transported. In general, control units suggested for these purposes heretofore have utilized operator controlled, manually adjusted pre-set cycle timing mechanisms. Operation of these prior art devices has accordingly required that an operator of the equipment select an estimated duty cycle which will take into account the transport speed of the processor; the length of film being processed, etc. This has, in turn, resulted in situations wherein the trailing-edge to leading-edge separation between successive sheets of film being fed into the processor has varied widely, and wherein, unless extreme care was exercised, there was a serious risk of overlap between successive sheets being processed. Moreover, any change in the transport speed of the processor required the operator to make a corresponding adjustment in the manually set cycle-time of the controller. As a result of these problems, inherent in the manual adjustments and attendant operator judgement which have characterized the prior art, proper operation of the equipment has depended upon the skill of an operator, has been comparatively time consuming in view of the manual adjustments and resetting operations required of him, has slowed down the overall operation of the processor, i.e., has reduced the processor dutycycle, and, in addition, has normally resulted in unnecessary comsumption of electrical power and water.

The present invention, recognizing these problems inherent in the electro-mechanical control units of the prior art, is intended to provide a new control unit which accomplishes the intended purposes of the prior art in a far more efficient and convenient manner while simultaneously obviating the various problems discussed above.

SUMMARY OF THE INVENTION In accordance with the present invention, a control unit operative to selectively energize the drier heater and blower motor circuits of a film processor, and operative to control the flow of wash water therein, comprises an electronic circuit which can be incorporated into the processor itself, and which synchronizes the drier circuit energization and water solenoid energization with the rate of film transport through the processor, rather than being dependent upon the manuallyadjusted pre-set cycle-timing techniques of the prior art. Successive films can be fed with constant trailingedge to leading-edge space separation, irrespective of transport speed and without risk of overlap, thus yielding a higher processor duty cycle when required. Transport velocity versus cycle-time matching adjustments are eliminated, and the pulse-type circuitry employed lends itself readily to the addition of analog or digital counting systems, or level detectors, capable of indicating the presence of a sheet of film at any particular location along the transport path.

The term film as used herein, and in the appended 7 claims, is intended to be generic to all types of silverhalide photosensitive materials requiring treatment in photographic processing machines. The term sheet is intended to cover all configurations of such materials.

The improved system of the present invention comprises four basic elements, i.e., a transport pulse generator, a film feed sensor, a slow integrator and power control circuit, and a fast integrator associated with a film-feeding indicator. The transport pulse generator produces a train of pulses, of constant duration and amplitude, which are fed to the slow and fast integrators governing the machine-control functions; and the integrators are, in turn, selectively rendered operational under the control of the film feed sensor.

In operation, when a sheet of film is fed into the processor, portions of the circuit prevent energization of the wash water solenoid and drier heater and blower motor circuits until the leading edge of the film sheet engages the film feed sensor, at which time the wash water solenoid and drier electrical circuits become and remain energized during the passage of the film sheet over the sensor. When the trailing edge of the same sheet of film passes beyond the film feed sensor, these circuits are conditioned to remain energized for a further period of time determined by the counting of a specific number of pulses by the slow integrator, to achieve a total time period of energization which is responsive to the transport speed and film length, and is sufficient to allow the trailing edge of the film sheet to pass completely through the processor and to reach the output catch tray. Upon elapse of this period of time, the wash water solenoid and drier electrical circuits are deenergized. In practice, the transport pulse generator produces nine pulses for each linear inch of film motion through the processor transport system, and the slow integrator in turn counts approximately 2,000 pulses (corresponding to approximately 222 inches of film path length, which is about 10 percent greater than the total transport path length in a typical film processor), before the slow integrator operates to deenergize the drier circuits and water solenoid.

When the trailing edge of the film sheet clears the film feed sensor, a fast integrator is also rendered operative to count pulses from the transport pulse generator. The output of the fast integrator controls an indicator, Le. a film feeding lamp, which is turned on when the leading edge of the film sheet engages the film feed sensor, and remains on until the fast integrator has counted approximately 63 pulses (corresponding to a trailing edge film advance of about seven inches through the transport path) at which time the film feeding" lamp is turned off to indicate to the operator that a new sheet of film can be fed into the processor. This portion of the circuit accordingly assures a constant trailing-edge to leading-edge space separation between successive sheets of film, irrespective of transport speed, thereby eliminating risk of overlap between successive sheets while maximizing the processor duty cycle.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing construction, operation, and advantages of the present invention will become more readily apparent from the following description and accompanying drawings in which:

FIG. 1 is a schematic diagram of an improved control circuit constructed in accordance with one embodiment of the present invention; I

FIGS. 2A through 2F inclusive graphically represent the operation of the circuit shown in FIG. 1 and FIG. 3 diagrammatically illustrates a film processor which embodies the control circuit of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The control system of the present invention is used in conjunction with a processor having a transport system for transporting material to be processed along a transport path toward and through a material treatment station. One such arrangement is shown in FIG. 3, wherein the processor constitutes a well known, commercially available automatic film processing apparatus comprising a plurality of material treatment stations i.e., a developer tank A, a fixer tank B, a wash tank C having a valve V associated therewith for discharging water to waste, and a drier tank D having a blower E therein associated with heater coils F. A sheet of film to be processed is fed from an input tray by a pair of driven film pickup rollers G, constituting a portion of the transport system, to tank A, is then transported through tank A, B and C in sequence by transport modules of known configuration located in each tank, e.g. driven roller or roller/belt systems, is then fed through squeegee rollers H, driven in synchronism with the remainder of the transport system, to drier tank D and is transported through said tank D by a further such transport module and thence through a processor exit slot into a catch tray where the film sheet is received in completely processed and dried condition. FIG. 3 further illustrates a film feed sensor 6 adjacent the input tray, and a control circuit associated therewith,

constituting the improvement of the present invention which'will now be described.

As described earlier, and as shown diagrammatically in FIG. 3, the control circuit of the present invention is intended to effect a saving of electrical power by inhibiting the drier heating (F) and blower motor (E) circuits of the film processor unless film is being transported through the processor; and also effects a reduction of water consumption by preventing wash water from flowing, via valve V, to waste in said processor except while film is being transported. The control circuit is shown in FIG. 1, and comprises four basic elements, i.e., a transport pulse generator, a film feed sensor, a slow integrator and associated power control system, and a fast integrator and associated film-feeding indicator.

The transport pulse generator operates to synchronize the overall circuit with the rate of film transport through the processor, thereby eliminating the manual adjustments which have characterized the prior art, and causing the circuit to automatically adjust its operation to conform to any chosen transport speed. The transport pulse generator is generally designated 1 and may take a variety of forms, e.g. optical, magnetic, mechanical, etc. and combinations thereof. In the embodiment shown in FIG. 1, transport pulse generator 1 comprises a light source 1a, preferably an infra-red light emitting diode (to avoid the risk of film fogging by actinic light), and an associated phototransistor light detector lb. Elements la and lb are disposed in juxtaposition to one another in a common assembly which straddles a light chopping disc lc which is rotated by the main drive shaft 1d of the processor transport mechanism. Main drive shaft ld rotates continuously whenever the processor is switched on, and each revolution of shaft 1d results in one inch of forward motion of the material transported through the developing, fixing, washing and drying stations A-D inclusive of the processor (see FIG. 3).

Chopping disc 1c has nine peripheral notches le spaced equidistantly around its circumference (the number of notches could, of course, be increased or decreased without departing from the invention); and as disc 10 rotates, it intersects and blocks the light path between light source la and light detector lb except during the passage of each notch through said light path. Whenever the light path between source la and detector lb is uninterrupted, phototransistor lb conducts hard, thereby generating current pulses which are synchronized with the film motion at a rate of nine pulses per linear inch of material travel.

The output of light detector lb comprises a wave form of somewhat rounded configuration, as illustrated at 20. This somewhat rounded waveform is fed to a shaping amplifier 2 which is used to square-up the pulse and, because amplifier 2 is overdriven by the input signal, its output waveform consists of constant amplitude positive-going pulses as illustrated at 21. The pulses 21 are applied to a differentiator and clipper stage 3. The

differentiation of waveform 21 yields narrow positive and negative-going pulses 22 which represent, respectively, the leading and trailing edges of squarewave 21. The positive-going portion of waveform 22 is eliminated by a diode clipping circuit in element 3, leaving a negative-going pulse 23 at the output of differentiator and clipper circuit 3; and pulse 23 is in turn fed to a one shot pulse generator 4 which produces a constant amplitude positive-going output pulse 24 of, for example, 1.5 milliseconds duration.

The various waveforms 20-24 are not to scale and have been added to FIG. 1 for illustrative purposes only. The elements 1 through 4, taken together, constitute the transport pulse generator and, as described, produce a series of pulses of constant duration and amplitude which are directly related in number to path length through the processor.

The output pulses from pulse generator 4 are fed via biased pulse gates 5 and 12, which remove any base line noise, to the inputs of slow integrator 7 and fast integrator 13. These two integrators operate, in effect, to count" different numbers of said pulses; and the integrators are rendered selectively operative to effect this counting" function under the control of the aforementioned film feed sensor. This sensor, located beneath the film feed tray (see FIG. 3) at a position close to the nip of the film pickup rollers G at the input of the film transport system, detects the passage of each sheet of material over the feed tray as it is fed to the processor input, and prevents any counting of pulses by the slow and fast integrators 7 and 13 until the trailing edge of each sheet of film has cleared the film feed sensor.

In one embodiment of the invention, the film feed sensor may comprise a snap-action switch 6 having a low-force actuating arm which projects upwardly through a slot in the base of the feed tray to intersect the film path. Since it is customary to feed each film lengthwise into the processor with one edge of the film sheet in contact with the left hand side flange of the feed tray, the switch 6 is positioned to the right of the left-hand tray edge at a width-wise distance sufficient to intersect the forward path of the narrowest film to be conveyed. Further such switches, having their like contacts connected in parallel can, if desired, be posi-- tioned at other locations across the width of the film tray if, for example, it is desired to detect the passage of a plurality of individual films fed concurrently in spaced relationship across the width of the tray. Known illustrated operationally in FIG. 2A') the film feed sensor switch 6 comprises two sections, i. e., a switch blade 6a associated with contacts 6b and 6c, and a switch blade 6d associated with contacts 6e and 6f. These two sections of the double-pole double-throw film feed sensor switch 6 are associated respectively with capacitors 7b and 13b, forming portions of slow integrator 7 and fast integrator 13, to be described subsequently. More particularly, switch blade 60 is connected to one electrode of slow integrating capacitor 7b, and its associated normally open contact 60 is connected to-the remaining electrode of capacitor 7b. Similarly, switch blade 6d and its associatednormallyopen c'o'ntact6f are connected to opposing ends of fast integrating capacitor 13b respectively.

Both switches 6a, 6c and 6d, 6f are open whenever of nine pulses per inch of film travel through the transport path, are thereby connected from one-shot pulse generator 4 to the input of the slow integrator 7 and are, in effect, counted therein. I

Slow integrator 7 comprises a commercially available operational amplifier connected as a bootstrap integrator, or staircase generator, having a storage capacitor 7b and associated current limiting resistor 7c. The successive input pulses which are supplied to the input of slow integrator 7 cause a negativegoing staircase voltage to be developed at its output terminal 70 which continues to increase in magnitude in a negative direction with each successive input pulse until the negative potential at terminal 7a reaches the triggering point of voltage level detector 8. When the triggering voltage of level detector 8 is exceeded (see FIG. 2D) the level detector conducts and causes relay driver transistor 9 to energize relay coil 10 so as to open normally-closed contact sets 10a, 10b and 10d, 10c associated therewith (see FIGS. 2E and 2F). The opening of contacts 10a, 10b ungrounds the input terminal of amplifier 7,

causing its output terminal 70 to assume a constant negative potential slightly greater than the 8 V. reference applied to voltage level detector 8, thereby holding it and relay driver 9 in conduction and maintaining relay. l0 energized. At the same time, the opening of contacts 10d, 10c removes power from controlled cir- The values of capacitor 7b and resistor 7c are chosen 7 to require the output voltage of slow integrator 7 to describe about 2000 negativegoing steps (corresponding to a transport path distance of approximately 222 film is not being fed-into the processor; but when asheet of material is aligned on the feed tray and moved forward, under either manual or automatic control, in

' the direction of transport, the leading edge of the film .deflects the actuating arm of switch 6 downwardly,

causing switches'6a, 6c and-6d, 6f to close, thereby dis-' charging capacitors 7b: and 13b. The capacitors 7b and 13b are maintained in this discharged state throughout the time required for the film sheet to traverse switch 6, and until the film sheet trailing edge clears the actuating arm of switch 6. At that instant of time,,the actuating arm of switch 6 is released, and switch blades 6a and 6d move away from their respective normally-open contacts 6c and 6f and into engagement with their normally-closed contacts 6b and 6e respectively, thereby removing the short circuit fromeach of capacitors 7b and 13b and permitting integrating actions to, commence in slow integrator 7 and fast integrator 13.

As discussed earlier, output pulses from one-shot pulse generator 4 are fed, via biased pulse gate 5, to the input of slow integrator 7. Integrator 7, in conjunction with voltage level detector 8 and relay driver 9, forms an automatic control circuit which maintains all processor functions in operation from the instant when .the leading edge of a film sheet actuates sensing switch 6 processor drier discharge slot. After triggering, this control circuit will remain in its energized state until it is reset by feeding of the next film sheet. At that time, storage capacitor 7b will be discharged by the closure of film feed switch contacts 60, 6c, as previously described, causing output terminal 7a to return to ground potential, thereby deenergizing relay [0 and reclosing its contacts 10a, 10b to remove the negative unbalancing voltage applied to amplifier 7 while, at the same time, reconnecting controlled circuits l7 totheir power vsource via contacts 10d, 10:: for a further period of full I cessor subsequent to extinction of film feeding" indiuntil shortly after the trailing edge of the same film sheet exits from the output slot of the drying section of the processor. It does this since the passage of the film trailing-edge beyond film sensor switch 6 removes the short circuit across capacitor 7b, enabling integrator 7 to commence its integrating operation. Pulses, at a rate processor operation (see the portions of FIG. 2 designated feed in film No. 2).

- A somewhat different mode of operation ensues if, as is often the case, a second film sheet is fed into the procator lamp 16 (to be described) and prior to exiting of the trailing edge of the preceding film from the drier discharge slot. In this event, the reclosing of film feed switch 6a, 60, due to introduction of the second film sheet intothe processor, will discharge the slow integrator storage capacitor 7b; and a newv integration cycle will be initiated as soon as the trailing edge of the second film sheet clears film feed switch 6, thereby maintaining the processor in continuous operation until discharge of the additional film, or films, has taken place.

The output pulses from one-shot pulse generator 4 are, in addition to being coupled to slow integrator 7, coupled via pulse gate 12 to the input of fast integrator 13. Fast integrator 13, in conjunction with film feed switch 6d, 6fcontrols the illumination offilm feeding lamp 16. Lamp 16 is visible to the operator (e.g., it is mounted on the processor control panel), and functions to advise the operator as to when it is permissible for him to feed a new sheet of film into the processor.

The operation of the fast integrator circuit is similar to that of slow integrator 7, except that lamp driver circuit 15 is arranged to energize lamp 16 until the negative-going voltage at the output terminal 13a of fast integrator l3 exceeds the reference voltage at voltage level detector 14. The values of capacitor 13b and resistor 130 are chosen to provide integration of only approximately 63 pulses in fast integrator 13 (corresponding to about 7 inches of film advance through the transport path); and when 63 pulses from one-shot pulse generator 4 have been integrated, the negativegoing staircase voltage at terminal 13a reaches the triggering point of voltage level detector 14. When this takes place, the output stage of lamp driver 15 becomes cut-off and lamp 16 is extinguished, thereby signifying that film may again be fed into the processor.

The output of the fast integrator circuit is initiated, simultaneously with that of the slow integrator, by actuation of film feed switch 6. Closing 'of contact set 6d, 6f discharges integrating capacitor 13b, and brings amplifier output terminal 130 to ground potential to light filmfeeding" lamp 16. Illumination of this lamp alerts the operator to the fact that an additional sheet of film should not be fed into the processor at that time. When the trailing edge of the film sheet entering the processor releases the actuating arm of switch 6, its contacts 6d, 6f reopen, and integration of nine pulses per inch of film advance commences in fast integrator 13. The negative going staircase voltage developed at output terminal 130 increases in magnitude with each successive input pulse until the potential at terminal 13a reaches the triggering point of voltage level detector 14, causing it to conduct and, as described above, to extinguish the "film feeding" indication via lamp driver 15.

When relay associated with the slow integrator becomes energized, the opening of contact set 10a, 10b ungrounds the input terminal of amplifier l3, causing its output to assume a constant negative voltage slightly in excess of the 8V. reference applied to level detector 14, thereby maintaining lamp 16 extinguished until the circuit is reset by feeding of the next film. The

fast integrator thus provides information, and a visible indication, as to when each film sheet should be fed into the processor; and the 63 pulse count achieved by integrator 13 enables such films to be conveyed in spaced succession, with a constant small trailingto leading-edge separation between them, whenever required. v p

Relay coil 10 is connected between relay driver 9 and a source of energization potential by means of a singlepole singlethrow manually operable switch 11. Switch 11 constitutes an override switch which normally has its contacts 11a, 11b closed to connect the power source to relay coil 10, permitting said relay to be energized when required. In the event of a control circuit failure of the type which would cause relay 10 to remain energized continuously, and thereby prevent energization of controlled circuits l7, switch 11 can be moved to its open position. This deenergizes relay 10 and enables the processor to function in conventional fashion while repairs to the control circuit are being effected.

When the processor is first turned on, and before the first sheet of film is fed, relay 10 may be in a deenergized state, causing the controlled circuits 17 to be temporarily energized, and indicator lamp 16 may be temporarily .on since, at that initial time, the outputs of slow integrator 7 and fast integrator 13 may be somewhat less negative than the 8V reference levels of voltage detectors 8 and 14. Because the sensor switch 6 is not, at that time, short circuiting capacitors 7b and 13b, an initial integration of pulses from pulse generator 1 occurs, causing the outputs of slow and fast integrators 7 and 13 to be driven negatively to their 8 volt levels in a start-up time interval which is dependent upon the previously existing residual charge in capacitors 7b and 13b. At the end of this initial integration period, the voltage level at the output of slow integrator 7 produces an output from relay driver 9 operative to energize relay 10 (thereby deenergizing controlled circuits l7), and the voltage level at the output of fast integrator 13 causes film feeding lamp 16 to extinguish. Subsequently, when the first film is fed into the processor, engagement of its leading edge with sensor switch 6 immediately zeroes the integrators 7 and 13, causing deenergization of relay l0 and, as a result, immediate energization of controlled circuits 17, and also causing immediate energization of lamp 16. The integrators are maintained in their zeroed condition so long as the sheet of film being fed actuates switch 6, and integration does not commence until the trailing edge of the film sheet passes beyond sensor switch 6, whereby the operation of the system is rendered independent of the length of the film sheet being processed, i.e. the controlled circuits remain energized for a period of time sufficient to permit egress of the trailing edge of the film sheet from the processor discharge slot.

While we have thus described preferred embodiments of the present invention, many variations will be suggested to those skilled in the art. By way of example, the slow and fast integrators, or either of them, can be replaced by analog or digital counting systems. Moreover, instead of using only one slow integrator, it is possible to provide several slow integrators having their inputs connected in parallel, each having a different integration time, and operative to perform different control functions, respectively. For example, one slow integrator could energize the watersolenoid after, for example, 900 pulses have been counted (corresponding to l00-inches of material transport, to take care of appropriate developing and fixing of said material) and a second slowintegrator could turn the water solenoid off after, for example, 1500 pulses have been counted, thereby assuring that the wash water is supplied only when it is absolutely needed. A variation of this type will achieve an even greater saving in water consumption.

Still other variations will be apparent to those skilled in the art. it must accordingly be understood that the foregoing description is intended to be illustrative only and not limitative of the present invention, and all such variations and modifications as are in accord with the principles described are meant to fall within the scope of the appended claims.

Having thus described our invention, we claim:

1. In a processing apparatus of the type comprising at least one material treatment station, means for transporting material to be processed along a transport path toward said station, means for producing a train of pulses having a repetition rate related to the rate of transport of said material along said path, pulse counter means, material detecting means disposed adjacent said transport path at a position upstream of said station for selectively rendering said counter means operative to count said pulses, and control means coupled to said counter means and responsive to a predetermined pulse count therein for controlling the state of operation of said material treatment station.

2. The combination of claim 1 wherein said material treatment station comprises an electrically energizable drier in an automatic film processor.

3. The combination of claim 2 wherein said control means is responsive to occurrence of said predetermined pulse count to de-energize said drier.

4. The combination of claim 1 wherein said material treatment station comprises a wash tank in an automatic film processor, said control means being responsive to occurrence of said predetermined pulse count to prevent water from flowing through said wash tank to waste.

5. In an automatic film processor of the type comprising a film processing section, an electrically energizable drier section, and transport means for transporting a sheet of film from a processor input location along a transport path through said processing section and drier section in sequence,

the improvement comprising means for monitoring the distance traveled by a sheet of film along said transport path, film detecting means disposed adjacent said processor input location and responsive only to the passage of the trailing edge of a sheet of film to said input location for rendering said monitoring means operative, and control means coupled to said monitoring means for de-energizing said drier section when the total transport distance traveled by a sheet of film being thereafter monitored by said monitoring means reaches a value sufficient for the passage of the trailing edge of said sheet of film completely through said processing and drier sections, the deenergization of said drier section thereby being rendered independent of the length of said sheet of film between its leading and trailing edges.

6. The combination of claim 5 wherein said film detecting means includes means responsive to passage of the leading edge of said sheet of film to said input location for causing said control means to energize said drier section.

7. The combination of claim 6 wherein said monitoring means comprises an electric signal generator coupled to said transport means for producing a succession of signals each of which represents a predetermined increment of the distance traveled by a sheet of film along said transport path.

8. In an automatic film processor of the type comprising a film processing section, an electrically energizable drier section, and a transport system for feeding a sheet of film along a transport path through said processing section and drier section in sequence, the improvement comprising detecting means located adjacent said transport path at a position upstream of said film processing section for detecting the presence of a sheet of film, a pulse generator coupled to said transport system for producing a train of electrical pulses representing increments of distance traveled by said film sheet along said path, means for counting said pulses, control means responsive to the counting of a preselected number of said pulses for altering the state of energization of said drier section, and further control means coupled to said detecting means for rendering said counting means inoperative when a sheet of film'actuates said detecting means and for rendering said counting means operative to count said pulses when the trailing edge of a film sheet has passed said detecting means.

9. The combination of claim 8 wherein said film processing section includes an electrically energizable solenoid for controlling the flow of wash water, said control means also being operative to control the state of energization of said solenoid.

10. The combination of claim 8 wherein said pulse generator comprises a radiant energy source and a radiant energy detector disposed in spaced relation to one another, a chopper disc disposed between said source and said energy detector, said disc being mounted for rotation at a rate related to said rate of film transport, and pulse shaping circuits coupled to said energy detector.

11. The combination of claim 8 wherein said counting means comprises a pulse integrator which includes an integrating capacitor, said further control means including switch means for selectively connecting, and removing, a discharging circuit across said capacitor.

12. The combination of claim 8 including further counter means coupled to said detecting means for counting said pulses when the trailing edge of said film sheet has passed said detecting means, a film feed indicator, and means responsive to the counting of a second preselected number of pulses, less than said first preselected number, by said further counter means for causing said film feed indicator to indicate that a further sheet of film may be fed into said processor.

13. The combination of claim 12 wherein each of said counting means comprises a staircase generator pulse integrator having an integrating capacitor, said further control means being operative to apply short circuits across the integrating capacitors of said pulse integrators when a sheet of film actuates said detecting means.

14. The combination of claim 13 including a pair of voltage level detectors coupled to the outputs of said pulse integrators respectively.

15. The combination of claim 14 wherein said control means, for controlling the energization of said drier section, includes an electro-mechanical relay having a coil adapted to be selectively energized under the control of one of said voltage level detectors.

16. The combination of claim 15 including a manually operable override switch in series with said relay coil for selectively preventing energization of said coil.

17. The combination of claim 15 wherein said film feed indicator comprises a lamp the energization of which is under the control of the other of said voltage detectors. 

1. In a processing apparatus of the type comprising at least one material treatment station, means for transporting material to be processed along a transport path toward said station, means for producing a train of pulses having a repetition rate related to the rate of transport of said material along said path, pulse counter means, material detecting means disposed adjacent said transport path at a position upstream of said station for selectively rendering said counter means operative to count said pulses, and control means coupled to said counter means and responsive to a predetermined pulse count therein for controlling the state of operation of said material treatment station.
 2. The combination of claim 1 wherein said material treatment station comprises an electrically energizable drier in an automatic film processor.
 3. The combination of claim 2 wherein said control means is responsive to occurrence of said predetermined pulse count to de-energize said drier.
 4. The combination of claim 1 wherein said material treatment station comprises a wash tank in an automatic film processor, said control means being responsive to occurrence of said predetermined pulse count to prevent wAter from flowing through said wash tank to waste.
 5. In an automatic film processor of the type comprising a film processing section, an electrically energizable drier section, and transport means for transporting a sheet of film from a processor input location along a transport path through said processing section and drier section in sequence, the improvement comprising means for monitoring the distance traveled by a sheet of film along said transport path, film detecting means disposed adjacent said processor input location and responsive only to the passage of the trailing edge of a sheet of film to said input location for rendering said monitoring means operative, and control means coupled to said monitoring means for de-energizing said drier section when the total distance traveled by a sheet of film being monitored by said monitoring means reaches a value sufficient for the passage of the trailing edge of said sheet of film completely through said processing and drier sections, the deenergization of said drier section thereby being rendered independent of the length of said sheet of film between its leading and trailing edges.
 6. The combination of claim 5 wherein said film detecting means includes means responsive to passage of the leading edge of said sheet of film to said input location for causing said control means to energize said drier section.
 7. The combination of claim 6 wherein said monitoring means comprises an electric signal generator coupled to said transport means for producing a succession of signals each of which represents a predetermined increment of the distance traveled by a sheet of film along said transport path.
 8. In an automatic film processor of the type comprising a film processing section, an electrically energizable drier section, and a transport system for feeding a sheet of film along a transport path through said processing section and drier section in sequence, the improvement comprising detecting means located adjacent said transport path at a position upstream of said film processing section for detecting the presence of a sheet of film, a pulse generator coupled to said transport system for producing a train of electrical pulses representing increments of distance traveled by said film sheet along said path, means for counting said pulses, control means responsive to the counting of a preselected number of said pulses for altering the state of energization of said drier section, and further control means coupled to said detecting means for rendering said counting means inoperative when a sheet of film actuates said detecting means and for rendering said counting means operative to count said pulses when the trailing edge of a film sheet has passed said detecting means.
 9. The combination of claim 8 wherein said film processing section includes an electrically energizable solenoid for controlling the flow of wash water, said control means also being operative to control the state of energization of said solenoid.
 10. The combination of claim 8 wherein said pulse generator comprises a radiant energy source and a radiant energy detector disposed in spaced relation to one another, a chopper disc disposed between said source and said energy detector, said disc being mounted for rotation at a rate related to said rate of film transport, and pulse shaping circuits coupled to said energy detector.
 11. The combination of claim 8 wherein said counting means comprises a pulse integrator which includes an integrating capacitor, said further control means including switch means for selectively connecting, and removing, a discharging circuit across said capacitor.
 12. The combination of claim 8 including further counter means coupled to said detecting means for counting said pulses when the trailing edge of said film sheet has passed said detecting means, a film feed indicator, and means responsive to the counting of a second preselected number of pulses, less than said first preselected number, by said further counter means for causing said film feed indicator to indicate that a further sheet of film may be fed into said processor.
 13. The combination of claim 12 wherein each of said counting means comprises a staircase generator pulse integrator having an integrating capacitor, said further control means being operative to apply short circuits across the integrating capacitors of said pulse integrators when a sheet of film actuates said detecting means.
 14. The combination of claim 13 including a pair of voltage level detectors coupled to the outputs of said pulse integrators respectively.
 15. The combination of claim 14 wherein said control means, for controlling the energization of said drier section, includes an electro-mechanical relay having a coil adapted to be selectively energized under the control of one of said voltage level detectors.
 16. The combination of claim 15 including a manually operable override switch in series with said relay coil for selectively preventing energization of said coil.
 17. The combination of claim 15 wherein said film feed indicator comprises a lamp the energization of which is under the control of the other of said voltage detectors. 